Random Minecraft Server Admin Question: Nether Portal Restrictions

The inability to build Nether portal networks was actually a major reason I struck out on my own hosting a server for friends and family. Why do so many of the larger servers restrict Nether portals?

I can sort of understand servers that only allow a set number of randomly placed portals: They create focal points for city construction and encourage the development of extensive nether rail networks. But so many servers have one portal at spawn and that’s that.

The original inspiration for the Nether were The Ways from The Wheel of Time: paths in an alternate dimension that while somewhat dangerous, would allow you to travel great distances quickly. It seems sort of weird to completely throw that idea out of the window.